A2 milk being poured into a glass.

If you have trouble digesting milk but have had no success with lactose-free varieties, a relatively new milk that's supposed to be “easier on digestion”  may have caught your eye.

Called a2, this version of cow’s milk, produced by The a2 Company, is now available at more than 12,000 retailers in the U.S., including big-box stores like Walmart and Costco. Ads for the product suggest that some people who think they’re lactose intolerant actually aren’t. Instead, they may be sensitive to a type of protein in milk called A1, which is found in regular cow’s milk (even the lactose-free variety). So can a2 help you? We looked into the research. 

Is It Lactose or Protein Intolerance?

There are good reasons to include cow’s milk in your diet. It packs a powerful nutritional punch, providing protein and fat as well as many key vitamins and minerals. “Milk is an excellent source of calcium, which is a nutrient that many people don’t get enough of yet is crucial for bone health,” says Charlotte Vallaeys, M.S., a nutritionist and Consumer Reports’ senior policy analyst for food and nutrition. But drinking regular milk can cause abdominal pain, bloating, diarrhea, and gas in some people. 

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Lactose intolerance is often blamed for these symptoms. Some people don’t produce enough of an enzyme called lactase, which digests lactose (a simple sugar in milk) in the small intestine. The degree to which people are lactose-intolerant varies, but most people can tolerate a cup or two of milk a day. Lactose-free milk, such as Lactaid, has lactase added to predigest the lactose.

Not everyone who has milk-related symptoms experiences relief when they drink lactose-free milk, however. That’s where a2 milk comes in. “In some cows, there’s a gene mutation that results in different variants of one of the major milk proteins [beta casein],” says Chad Dechow, Ph.D., an associate professor of dairy-cattle genetics at Penn State. Beta-casein makes up about a third of the protein in milk. Regular milk comes from cows that produce both A1 and A2 types of this protein, while a2 milk comes from cows that naturally produce only the A2 type.

Claim Check

“There is evidence that suggests the A1 protein is associated with digestive discomfort in some people,” Dechow says. But the research on the benefits of a2 milk is scant.

A small study (funded by The a2 Company) found that it may take some people significantly longer to digest milk that contains both the A1 and A2 protein than milk that only contains A2. That decrease in speed could lead to gastrointestinal inflammation, and symptoms like gas and abdominal pain.

A research review published in the journal Advances in Nutrition backs this up, but points out that studies comparing the effects of A1 and A2 on humans are limited (many were on rodents).

“There needs to be more large-scale, human trials,” says Sabrina Greenwood, Ph.D., an associate professor of animal nutrition at the University of Vermont. She adds that there are many proteins that vary in cow’s milk, and that may affect results as well. “When we compared two types of cows, we found more than 40 proteins that were different between them,” she says. “Any one of those could be causing differences [in symptoms] too.” 

Test for Yourself

The research backing up The a2 Company’s claims may be limited, but an easy test can determine whether the product works for you. “Consumers can’t always verify some of the claims on food labels," says Vallaeys. “But a2 milk’s promise is one you can check for yourself—and if it doesn’t work, you’ll know that a2 isn’t the solution for you."

In blind taste tests of a2 milk and Lactaid, CR’s professional taste testers reported that both tasted similar to regular milk and to each other. But Lactaid had a slightly sweeter (but not objectionable) taste.

If you don’t have problems digesting milk, though, there’s no reason to pay the premium price for a2 milk or Lactaid. Nutritionally, a2 milk and lactose-free milk are pretty much equal to regular milk, but both can be more expensive. For example, at Walmart, 64 ounces of Great Value (Walmart’s house brand) milk costs $1.73 for conventional and $3.12 for organic. Lactaid costs $3.88 for 64 ounces, and a2 milk costs $4.29 for 59 ounces.

Editor's Note: This story has been updated to include new information on the number of retailers where a2 Milk is available.